Sharpest ever view of the Sun

The first images from the Swedish 1-m Solar Telescope on the Canary Island of La Palma are presented in Nature on November 14. The images are the most detailed ever obtained of the Sun - among the new solar features uncovered are hitherto unknown phenomenae in sunspots.

The telescope was opened in March this year and is operated by the Institute for Solar Physics of the Royal Swedish Academy of Sciences. Its objective lens has a diameter of one meter and the telescope is designed to minimize problems from turbulent air that blur the images. The telescope tube is evacuated and a mirror in the beam adjusts its shape a thousand times a second to counteract the atmospheric blurring. This makes the images the sharpest ever of the Sun. The resolution achieved is 1,200 times better than normal eyesight (20/20 vision).

The new images show thin dark cores in the thread-like structures that surround the darkest part of a sunspot. The nature of these cores is unknown. Sunspots are regions with strong magnetic fields. Solar magnetic fields can disturb telecommunications and satellite operations.

Notes

Space observatories studying the Sun are equipped with too small telescopes to be able to reach the resolution of the Swedish 1-m Solar Telescope. However, they can access radiation which does not pass through the atmosphere, such as X-ray radiation. Therefore, solar telescopes in space give a complementary view of the Sun. Earth-based solar observing suffers much from the turbulence in the earth's atmosphere and requires a location with relatively steady air. The observation site on top of the extinct volcano of La Palma is among the best in the world.